Water tube boiler



April 14, 1942. J, CHEmsq-ER ETAL 2,279,618

WATER TUBE BOILER F'iled May 27, 1940 2 Sheefcs-Shee'fl l Patented Apr. 14, 1942 UNITED STATES ATENT FFICI'.

WATER TUBE BOILER Joseph L. Chedister and Thomas J. Engel, St. Paul,

Application May 27, 1940,`seria1 No. 337,383

y the rebox or combustion chamber, indicated by 2 Claims.

This invention relates to and provides an extremely simple and highly efficient improved boiler of the water tube type and, generally stated, consists of the novel devices, combinations of devices and arrangement of parts hereinafter described and defined in the claims. The improved furnace is especially adapted for use in connection with oil burners or gas burners, but may utilize the ordinary coal-burning rebox. The invention consists in a novel arrangement of the flame passage in the tubes. The Vliame duct passage involves upper and lower portions and an oblique connecting portion combined to form a sort of Z-Z shaped passage. By this flame duct or passage the flames or hot products of combustion will be directed in a general downward course, while the cold water will be brought into the water tubes at the lower portion of the flame duct and will be delivered in an upward direction. The advantage of this arrangement is that the products of combustion, even when brought to a comparatively low temperature, will be higher than the temperature of the introduced water and will act upon the same as long as the temperature of the products of combustion are higher than that of the returned water.

We have found that in a flame duct or passage of the character above indicated the temperature will be very much higher at the top than at the lower portion. For example, in the upper approximately horizontal run or portion of the flame duct the temperature at the top will frequently be as much as fifteen hundred (1500) degrees F., while the temperature at the bottom of the said upper run will be say six hundred (600) degrees F. The efficiency of the furnace in our arrangement is very much increased by placing the water tubes at the very top or highest practical position, especially in the upper run of the ame passage, but preferably also in the oblique and lower run of the fiame passage.

A commercial embodiment of the invention is illustrated in the accompanying drawings wherein like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a front elevation of the improved furnace, some parts being broken away;

Fig. 2 is a fragmentary front elevation of the furnace with the upper water header of the de- Vice removed to show the ends of the water tubes; and

Fig. 3 is a vertical front to rear section taken approximately on the line 3-3 of Fig. 1`

In the arrangement illustrated in the drawings the numeral 5, is an insulated structure that receives'the initial heat from an oil burner'indicated as an entirety by the numeral 6. The combustion chamber 5, at the top, opens directly into the upper run I of the flame duct. This name duct 1 quite closely approaches a horizontal, but is preferably slightly inclined. At its delivery end the flame duct 'I leads into an oblique flame duct 8 which, in turn, leads into a lower flame duct 9. Run or portion 9 of the flame duct is also preferably slightly inclined and it leads to a stack or outlet II). The runs or portions 1, B and 9 extend through a casing that is preferably of sheet metal and which is indicated by the numeral II. The sides of the runs or portions 1, 8 and 9 of the flame passage may, in some instances, extend to and be formed as part of the casing I I, but, as shown, and for a purpose presently to be noted, terminate somewhat short of the sides of said casing so as to leave air channels I2 for the upward movement of air within the casing II. Also the casing II may be provided with an` air inlet I3 and with an air outlet IlI- for a purpose that will also presently appear as a secondary feature of the invention.

The water tubes I5, at their upper ends, extend through the header plate I6 of an upper header box I'I, which latter is rigidly but detachably secured by machine screws I8, or the like. Just below the header box II the furnace structure is provided with a rigidly secured but detachable plate I9 that normally closes a cleanout passage 2D. At their lower ends the water tubes I5 extend through a header plate 2| to which a return header box 22 is rigidly but detachably secured by machine screws 23, or the like. The numeral 24 indicates a cold water return. pipe that opens into the header box 22, and the numeral 25 indicates a hot water outlet or delivery pipe that leads from the upper header box II. `The numeral 26 indicates a plate detachably secured by machine screws 21, or the like, to normally close a clean-out opening 28.

The upper portion 'I of the flame duct is preferably of considerable depth and tapered slightly toward the point of junction of the oblique portion 8. While the upper run' I of the fiame duct closely approaches a horizontal, still it is important that the upper plate thereof be downwardly inclined so that the hot flames will tend to hug the upper surface of said run 1. It is also now important to note that the Water tubes I5 are placedv as closely as practical to the upper wall or surface of the run 1 where the flames, as

above indicated, will be at the relation approximately of fteen hundred (1500) degrees F. in

the upper portion as against six hundred (600) degrees F. in the lower portion. Very much the same advantage is obtained in the oblique run 8 and in the lower run 9, by placing the tubes nearer to the upper than to the lower portions of the duct.

With this arrangement, and with the assumed temperatures in the upper run, above stated, the products of combustion can be taken out of the stack I0 at a temperature of approximately one hundred fty (150) degrees F. to act upon the cold water returned from the return header box 22 at a temperature of, say, seventy-live (75) de.- grees F. The advantages of these features, of course, are obvious, as they result in economy in the transfer of heat from the products of combustion to the water in the tubes.

While it is not necessary that the air within the casing Il be circulated to and from the exterior thereof, still the arrangement shown gives a Very simple and eicient way of utilizing the heat radiated from the air ducts to raise the temperature of air which may be delivered to a dwelling as an auxiliary heater and to furnish a circulationof air to the room or dwelling to be heated. By placing water pans within the casing Il such air can be humidied. Other changes may also be made within the scope of the invention herein disclosed and claimed.

What we claim is:

1. In a water tube boiler, a combustion chamber having a ame discharge passage in its upper portion, a tortuous ame duct leading continuously downward from the flame discharge passage of said combustion chamber, said flame duct, at its extreme lower end, having a iiue outlet connection for the final discharge of the products of combustion, a water inlet header at the lower end of said iiame duct, a water outlet header at the upper end of said name duct, and tortuous water tubes extended through said flame duct in a direction continuously downward from said water outlet header to said water inlet header, said iame duct being of decreasing crossesection in a direction from its upper receiving toward its lower flame-delivery end, and said tubes being arranged to closely followr the overlying upper walls of said name duct.

2. In a water tube boiler, a combustion chamber having a iiame discharge passage at its upper portion, a flame duct leading downward from the llame discharge passage of said combustion chamber, said flame duct at its extreme lower end having a ue outlet leading directly to the exterior of said casing and having a final discharge conduit extended upward therefrom at the exterior of said casing, a water inlet header at the lower end of said flame duct, a water outlet header at the upper end of said flame duct, and a water tube extending through said flame duct in a direction downward from said water outlet header to said water inlet header, said flame duct being of decreasing cross section in a direction from its upper flame-receiving end toward its lower iiame-delivery end, and said tubes being arranged to closely follow the overlying upper walls of said flame duct.

JOSEPH L. CHEDISTER. THOMAS J ENGEL. 

